This invention relates to aqueous printing inks and, more particularly, to aqueous pigmented ink jet ink compositions suitable for use in direct printing of durable images on an untreated vinyl substrate and to a process of using the ink to create a durable printed image direct to vinyl.
Ink jet ink printing is a form of digital printing in which droplets of ink are made to be ejected (i.e., "fire") from an orifice in a printhead or a spray nozzle in response to an electronic signal from, for example, a computer. Examples of ink jet printing include the thermal ink jet printing, piezoelectric ink jet printing, continuous ink jet printing and air brush printing.
In the past decade, ink jet printing, particularly the thermal and piezo forms, has become extremely popular for home office, small office and personal printer applications, primarily due to its relatively low cost, speed and quite operation. In more recent years, the popularity of ink jet printing has increased even further due to the introduction of systems (printers, software, media and inks) offering very high quality (near photographic) color and graphics capabilities.
Despite the rapid rise in popularity of ink jet printing in the office and home environments, this form of printing has had a more modest rate of acceptance in the large format and very large format applications. In general, the terms "large format" and "very large format" are used to define a class of printers that operate with a particular size media. For example, large format is commonly used to mean printers utilize media of not less than 17 inches in the smallest dimension and very large format is normally used to mean printers that utilize media of not less than about 60 inches in the smallest dimension. Such printers are used for applications such as banners, signage, displays, posters and billboards.
The use of ink jet printing in the large and very large format applications (for convenience, collectively referred to as "large format") has important advantages, not the least of which is the savings in short production runs over more traditional analogue printing methods. Yet, there are also disadvantages. For example, the types of final products produced for these applications may be subject to the elements in outdoor usage (e.g. billboards and other signage applications), and thus need to be far more lightfast, waterfast, abrasion resistant than typically required for office or home printing applications. Most ink jet inks, particularly the aqueous inks that are preferred for well-known environmental reasons, are dye-based and lack the desired waterfastness and lightfastness. Pigmented ink jet inks are generally more lightfast and waterfast than their dye-based counterparts. However, aqueous inks in general don't print well (or at all) on the vinyl and other hydrophobic, durable substrates that are commonly used in large format printing applications. Thus, it is often required that the substrates be pre-treated to accept the ink and/or post-treated to render the image sufficiently waterfast, lightfast and/or durable for the intended use, which adds considerably to the cost.
Accordingly, there is a need in the art for aqueous ink jet inks that are capable of producing durable, waterfast, lightfast images directly on vinyl or other hydrophobic substrates without any need for pre- or post-treatment.